svn commit: r262611 - in head/contrib/llvm: include/llvm/MC lib/MC

[Dimitry Andric]

Author: dim
Date: Fri Feb 28 17:12:31 2014
New Revision: 262611
URL: http://svnweb.freebsd.org/changeset/base/262611

Log:
  Pull in r196874 from upstream llvm trunk:
  
    Fix a crash that occurs when PWD is invalid.
  
    MCJIT needs to be able to run in hostile environments, even when PWD
    is invalid. There's no need to crash MCJIT in this case.
  
    The obvious fix is to simply leave MCContext's CompilationDir empty
    when PWD can't be determined. This way, MCJIT clients,
    and other clients that link with LLVM don't need a valid working directory.
  
    If we do want to guarantee valid CompilationDir, that should be done
    only for clients of getCompilationDir(). This is as simple as checking
    for an empty string.
  
    The only current use of getCompilationDir is EmitGenDwarfInfo, which
    won't conceivably run with an invalid working dir. However, in the
    purely hypothetically and untestable case that this happens, the
    AT_comp_dir will be omitted from the compilation_unit DIE.
  
  This should help fix assertions occurring with ports-mgmt/tinderbox,
  when it is using jails, and sometimes invalidates clang's current
  working directory.
  
  Reported by:	decke
  MFC after:	2 weeks
  X-MFC-With:	r261991

Modified:
  head/contrib/llvm/include/llvm/MC/MCContext.h
  head/contrib/llvm/lib/MC/MCContext.cpp
  head/contrib/llvm/lib/MC/MCDwarf.cpp

Modified: head/contrib/llvm/include/llvm/MC/MCContext.h
==============================================================================
--- head/contrib/llvm/include/llvm/MC/MCContext.h	Fri Feb 28 16:51:33 2014	(r262610)
+++ head/contrib/llvm/include/llvm/MC/MCContext.h	Fri Feb 28 17:12:31 2014	(r262611)
@@ -278,6 +278,7 @@ namespace llvm {
     /// This can be overridden by clients which want to control the reported
     /// compilation directory and have it be something other than the current
     /// working directory.
+    /// Returns an empty string if the current directory cannot be determined.
     StringRef getCompilationDir() const { return CompilationDir; }
 
     /// \brief Set the compilation directory for DW_AT_comp_dir

Modified: head/contrib/llvm/lib/MC/MCContext.cpp
==============================================================================
--- head/contrib/llvm/lib/MC/MCContext.cpp	Fri Feb 28 16:51:33 2014	(r262610)
+++ head/contrib/llvm/lib/MC/MCContext.cpp	Fri Feb 28 17:12:31 2014	(r262611)
@@ -47,8 +47,8 @@ MCContext::MCContext(const MCAsmInfo *ma
   AllowTemporaryLabels(true), DwarfCompileUnitID(0), AutoReset(DoAutoReset) {
 
   error_code EC = llvm::sys::fs::current_path(CompilationDir);
-  assert(!EC && "Could not determine the current directory");
-  (void)EC;
+  if (EC)
+    CompilationDir.clear();
 
   MachOUniquingMap = 0;
   ELFUniquingMap = 0;

Modified: head/contrib/llvm/lib/MC/MCDwarf.cpp
==============================================================================
--- head/contrib/llvm/lib/MC/MCDwarf.cpp	Fri Feb 28 16:51:33 2014	(r262610)
+++ head/contrib/llvm/lib/MC/MCDwarf.cpp	Fri Feb 28 17:12:31 2014	(r262611)
@@ -467,7 +467,8 @@ static void EmitGenDwarfAbbrev(MCStreame
   EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
   EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
   EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
-  EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
+  if (!context.getCompilationDir().empty())
+    EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
   StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
   if (!DwarfDebugFlags.empty())
     EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
@@ -643,8 +644,10 @@ static void EmitGenDwarfInfo(MCStreamer 
   MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
 
   // AT_comp_dir, the working directory the assembly was done in.
-  MCOS->EmitBytes(context.getCompilationDir());
-  MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
+  if (!context.getCompilationDir().empty()) {
+    MCOS->EmitBytes(context.getCompilationDir());
+    MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
+  }
 
   // AT_APPLE_flags, the command line arguments of the assembler tool.
   StringRef DwarfDebugFlags = context.getDwarfDebugFlags();